1. Field of the Invention
The present invention is related to power measurement systems, and more specifically to calibration of a non-contact sensor that includes an electrostatic field sensor for detecting the phase and/or magnitude of a voltage on a wire of a power distribution system.
2. Description of Related Art
A need to measure power consumption in AC line powered systems is increasing due to a focus on energy efficiency for both commercial and residential locations. In order to provide accurate measurements, the characteristics of the load must be taken into account along with the current drawn by the load.
In order to determine current delivered to loads in an AC power distribution system, and in particular in installations already in place, current sensors are needed that provide for easy coupling to the high voltage wiring used to supply the loads, and proper isolation is needed between the power distribution circuits/loads and the measurement circuitry. Further, in order to determine the power consumption of an AC load, further information about the voltage supplied to the load is desirable, in particular the phase of the AC line voltage with respect to the measured current and in some instances, the magnitude of the AC line voltage. Therefore, sensors have been developed that include voltage sensing via electrostatic field measurement.
Non-contact current sensors provide for easy installation, circuit isolation and other advantages in power measurement systems. However, such sensors may vary in fabrication, installation and application and the relationship between the measured voltage phase and/or magnitude and the output of the sensor may not be well established.
Therefore, it would be desirable to provide techniques for calibrating non-contact voltage sensors and systems including such calibration.